Ophthalmologists have recognized that medicaments administered to the eye by drops drain from the eye and are absorbed into the blood stream. This presents a two fold problem. First, the drug absorbed from the eye to the blood stream can cause undesirable side-affects. Second, because the eyedrop medication quickly drains from the eye into the blood stream, contact time between the medicament and the eye is undesirably shortened, with the result that the medicine does not have the desired affect on the condition being treated.
Ocular medications, when instilled into the eye drain away from the eye through the lacrimal system into the nasopharynx. This process takes several minutes depending upon the viscosity of the medication instilled. Drainage of medication away from the eye decreases contact time with the conjunctiva and cornea, and hence decreases ocular absorption. The drainage through the lacrimal system removes the drops from the eye and places the drops in contact with the nasal mucosa. The nasal mucosa allows for rapid absorption of medications into the blood stream. Certain medications can cause generalized side effects. Glaucoma medications, especially the class called beta-blockers, have been associated with significant morbidity, as well as, mortality from cardiovascular and pulmonary side effects.
Various solutions to the problem of systemic absorption of medicaments from the eye into the blood stream have been proposed in the medical literature.
Huang et al--American Journal of Ophthalmology, Vol. 107, February 1989 pages 151-155 discuss several methods for maximizing contact time between the eye and medication. In the article they state that,
". . . most topical ophthalmic medications with intraocular sites of action penetrate the eye through the cornea, conjunctiva, or sclera. The amount of medication absorbed is influenced by the amount of contact time between the medication and the ocular surfaces. Most of an eyedrop is lost to drainage within 15 to 30 seconds after instillation, which includes rapid drainage of 80% or more of the volume through the nasolacrimal system. Inhibition of this rapid drainage may lengthen the contact time of the medication with the eye and increase its absorption and efficacy. PA1 Inhibition of drainage through the nasolacrimal system may be achieved by manual occlusion with a fingertip, by placing plastic or collagen plugs into the puncta, or by permanently closing the puncta with cautery or laser. Nasolacrimal occlusion with fingertip pressure as a means of increasing ocular absorption of topical ocular medications has been proposed. Many patients, however, are unable to practice proper manual nasolacrimal occlusion." PA1 "Topically applied ophthalmic medications can attain sufficient serum levels via absorption into conjunctival, nasal, oropharyngeal and gastrointestinal mucosa to have systemic effects and thereby interact with other drugs. In fact, topical administration to the eye has been likened to intravenous rather than oral administration because a high percentage of the absorbed drug avoids hepatic first-pass metabolism; thus, drugs administered by this route can attain higher levels relative to dose than if administered orally. PA1 It is important to remember that even where the potential for drug interaction exists, there are methods to reduce systemic absorption. Nasolacrimal occlusion, a technique in which digital pressure on the periphery of the nasolacrimal drainage system obstructs drainage to the nasopharyngeal mucosa, has been shown to significantly decrease systemic absorption. Eyelid closure for five minutes following drug application also achieves the same purpose by inhibiting nasolacrimal pump action."
Urttic et al--Survey of Ophthalmology Vol. 37, No. 6 May--June 1993 pages 435-456 discusses in a review article methods for minimizing the systemic absorption of topically administered ophthalmic drugs. One of the ways suggested to increase ocular absorption and minimize systemic absorption was punctual occlusion, to block ocular drainage of the eyedrop from the conjunctival sac. This method involves applying the drops and pressing the inner ocular corners near the bridge of the nose with the fingers for 30 seconds to several minutes.
Gerber et al--Survey of Ophthalmology, Vol. 35 Number 3, November--December 1990, pages 205-218 states that:
The eyelid closure method of nasolacrimal occlusion involves the steps of tilting the head back and gently pulling down the eyelid to form a "V" pocket between the eye and the lower lid; placing drops of medicine in the eye; closing eyes and keeping head tilted back for 30 seconds to assure absorption of medication into the eye.
Methods involving the combination of punctual occlusion along with eyelid closure are recommended by many ophthalmologists.
Muenzler--Geriatric Ophthalmology Vol. 2 (1), January/February 1986, pages 19-23 in a discussion of the treatment for "dry eye" suggests another method of punctual occlusion using punctum plugs. Punctum plugs made of silicon supplied by Eagle Vision used to occlude the punctum and canaliculus are available to ophthalmologists.
Collagen implants have been experimentally implanted into the canaliculus as temporary implants to test for various abnormalities of the eye, such as, redness, burning, tearing, dry eye conjunctivitis, etc. If the complained of condition improves with the implant, the doctor considers permanent closure of the canaliculus. (Ophthalmology Times, Vol. 10 No. 23 Dec. 1, 1985).
A review of the literature indicates that the medical profession has recognized a number of ways to prolong contact time between medication and the eye, however none of the prior art has recognized applicants' occlusive device or method of employing such a device to prolong contact time between the eye and the medicament applied to the eye.